LS3 Engine Swap in a 1968 Chevrolet C10 - A Swap Worth Talking About

Street And Performance's LS3/6L80E Combo Redefines Radical When Paired With A Chevy C10

Our hobby is at the precipice of a dramatic trend shift that will determine which trucks are being customized regularly from here on out and what mods are being performed. Due to a number of economic factors, a resurgence of older iron (pre-2000) making a comeback in the custom scene is taking place. Fullsize trucks are cheap today and engine swaps are an economical way to inject some new life and modern performance into an older truck. Many of today's hottest swaps aren't the traditional anemic small-block-to-rip-snortin'-big-block affair either. Lots of sport truck owners have learned that double-digit fuel economy is just a fuel-injected engine and electronic overdrive tranny swap away.

One swap that is on fire as of late is the LS1 and 4L60E automatic tranny into GM C10 and C/K series trucks. You can find 300hp 5.3L versions of this fantastic iron block, aluminum-headed engine in the junkyard for a song. It's not unheard of to score the engine, trans, computer, and drive-by-wire pedal assembly for less than $2,000 at a boneyard because thousands of donor Chevy Silverado and GM Sierra pickups came standard with this combo.

Street and Performance has this swap and many others down pat, thanks to its own line of conversion parts and steady supply of engine, transmission, and accessory cores. What got us really excited about this story though is that the company just swapped a brand-new LS3 engine and six-speed automatic trans into a '68 Chevy C10 truck! The thought of 430 horsepower for blasting away from a stoplight and six gears for highway cruising in a standard cab truck really made us drool, so we had to know how it was done.

Follow along with the pictures for an overview of the changes the truck needed, and if you've got more questions or want to order parts then call the shop. Street and Performance has a massive catalog and instructional DVD to help get you started. Check it out!

What's Going Under The Hood?The EngineGM part number 19201992 is the new 430hp LS-3 fuel injected crate engine. It's an all-aluminum 376ci powerhouse with a 6,600 rpm redline that first arrived in the '08 Corvette and is now available through GM Performance Parts dealers. Amazingly, this small-block belts out 424 lb-ft of torque, which for a pushrod V-8 engine of this size is simply stunning. It's the right motivation for a sport truck.

The TransmissionThere are a couple of different variations of this transmission, but Street and Performance picked the 6L80E for the Pontiac GTO, which is part number 17803868, because it has a low-profile tranny pan for added ground clearance.

Part One: Engine Transplant Prep

1. After removing the complete drivetrain and accessories from the truck, the LS-3 is prepped for installation. First, the water pump is drilled and tapped to plumb a steam line from the pump to the cylinder heads. This is done to prevent steam pockets from building up in the cooling passages and causing hot spots to form in the block.

1. After removing the complete drivetrain and accessories from the truck, the LS-3 is prep

2. Next, S&P conversion mounts are bolted onto the sides of the aluminum block. Note that like most late-model GM products, everything on this engine is threaded for metric fasteners, which S&P provides with its kits. The LS motor mount location is several inches farther forward on the block than the original small-block engine that this truck came with. The conversion mounts fix this problem.

2. Next, S&P conversion mounts are bolted onto the sides of the aluminum block. Note that

3. The engine is flipped upside down on the engine stand so that a Camaro-style oil pan can replace the Corvette-style pan that came on the engine and add clearance in the sump area. S&P provides excellent instructions on its website for torque specs on every fastener.

3. The engine is flipped upside down on the engine stand so that a Camaro-style oil pan ca

4. The LS-3 is then flipped right-side-up once again, so that the S&P oil pressure sending until adapter can be installed at the rear of the block. This is adapter has three ports: a 16mm male, 16mm female, and 1/8-inch npt port. The metric ports thread into the block and to a sensor for the computer and the npt port makes it possible to run the factory oil pressure gauge. It's a necessary and trick piece.

4. The LS-3 is then flipped right-side-up once again, so that the S&P oil pressure sending

Tech TipReluctant Recipient CombinationsNot all LS engines are created equal. In fact, it's possible to have two LS1s from different model years that require completely different computers and sensors. Why is that? Well, the rear of the LS crankshaft has a round ring called a reluctor wheel. The reluctor wheel is used by the computer to determine the position of the crankshaft during each combustion cycle. There are two different wheels used by GM. One is a 24-tooth wheel and the other is a 58-tooth wheel. They are easily identified by looking into the passenger side of the engine block through a port located behind the starter. Or you can look at the plug that's hiding this port. If the plug is gray in color, the engine has a 58-tooth wheel and if the plug is black, then the crank has a 24-tooth wheel.

It gets even weirder now. Late-model Cadillac Escalades powered by new LS engines have variable cam timing, which the truck and car engines don't have. So always contact an experienced LS engine swap specialist like Street and Performance before you buy any swap parts, whether they are new or used. Compatibility is a big issue with the latest and greatest high-performance computer-controlled hardware from GM.

Part Two: Droppin' The Bomb

1. Test-fitting the engine into the C10 engine bay without the transmission or radiator installed. Note that LS2, LS3, LS7, LS9-powered Corvettes have a flat water pump pulley. If your donor engine came from an earlier-model Camaro or Trans Am, it also uses this type of water pump, but the Corvette balancer is 3/4-inch shorter for more radiator and electric fan clearance.

1. Test-fitting the engine into the C10 engine bay without the transmission or radiator in

2. The plastic intake manifold was removed earlier to prevent damage when installing the engine. Here, it's re-installed and the hardware is first torqued to 44 lb-ft and then 89 lb-ft.

2. The plastic intake manifold was removed earlier to prevent damage when installing the e

Part Three: Accessorize It!

1. It's time to dress up the engine with S&P's polished accessories. This is the company's new water pump cover.

1. It's time to dress up the engine with S&P's polished accessories. This is the company's

2. And this is the idler bracket kit, which bolts to the engine block and cylinder heads and is the key to mounting the A/C compressor and alternator.

2. And this is the idler bracket kit, which bolts to the engine block and cylinder heads a

3. The ignition coil packs are re-installed onto the valve cover brackets now. It's not necessary to remove them prior to installing the engine, but it does add clearance near the back of the head and firewall. Notice that polished bracket bolted to the cylinder head-that's where the A/C compressor will end up.

4. The Sanden 508 compressor has several advantages. First off, it works with the existing A/C system and features rear exit A/C lines for a more direct plumbing route.

4. The Sanden 508 compressor has several advantages. First off, it works with the existing

5. On the opposite side of the engine, S&P adds a chrome-plated factory GM 140-amp alternator, which has enough juice output for a fuel-injected engine and all the accessories in a truck, like the audio system, lighting, electric fuel pump etc.

5. On the opposite side of the engine, S&P adds a chrome-plated factory GM 140-amp alterna

6a. The serpentine belt isn't pictured, but here you can see where the adjustment comes from. Belt-tension is set via a pair of these threaded rod ends. It's tapped with a right-hand thread on one end, and a left-hand thread on the other end. This makes adjusting the belt tension as easy as turning the shaft with a wrench and then tightening the jam nuts to lock it in place.

6a. The serpentine belt isn't pictured, but here you can see where the adjustment comes fr

6b.

7a. This kit features S&P's mid-length thermal coated headers. The flanges are cut from stainless steel and the 2-1/2 inch primary tubes easily clear the framerails, steering linkage, and starter. If you look closely at the rear of the head you'll see the sending unit for the coolant temperature gauge.

7a. This kit features S&P's mid-length thermal coated headers. The flanges are cut from st

7b.

Part Four: The Fuel System

1. To provide fuel to the engine, this custom S&P rear exit fuel line was added. It runs down to the framerail where it connects to the factory fuel lines.

1. To provide fuel to the engine, this custom S&P rear exit fuel line was added. It runs d

2. A '99-and-up Corvette fuel pressure regulator and filter kit was mounted to the passenger-side framerail and connected to steel braded fuel lines via AN-6 fittings. The new lines were then run to the rear of the chassis, where they meet up with a new fuel cell.

2. A '99-and-up Corvette fuel pressure regulator and filter kit was mounted to the passeng

3. The really cool part about S&P's replacement fuel cell is that you can ditch the one that originally sat behind the factory bench seat. That adds precious cargo room inside the cab. But, this cell also features the correct sending unit to work with your fuel level gauge, ports for return and supply lines, and an in-tank electric fuel pump. Don't forget you'll need to shave the fuel filler hole in the rear cab pillar if you swap tanks.

3. The really cool part about S&P's replacement fuel cell is that you can ditch the one th

Part Five: Steering & Cooling

1a. S&P's accessory kit adds a factory GM power steering unit. In some applications, there's enough room to have a self-contained fluid reservoir, but in this truck the reservoir had to be mounted on the core support like factory big-block trucks had. The factory steering box is connected to the pump using supplied stainless steel braided lines. It's important that the lines be rated for 19 inches of vacuum, not pressure, and that these smaller GM power steering pumps use cold climate fluid. This keeps steering noise to a minimum.

1a. S&P's accessory kit adds a factory GM power steering unit. In some applications, there

1b.

1c.

2. Griffin provided a custom aluminum radiator that had both outlets on the passenger side and integral electric fan mounts and a built-in trans cooler.

2. Griffin provided a custom aluminum radiator that had both outlets on the passenger side

Part Six: Shifty!

1. Before installing the new trans, the engine is adjusted so that the rear is 1-1/2 to 2-1/2 degrees down. This is done to put the driveline in proper alignment with the rearend yoke, keeping the U-joints happy.

1. Before installing the new trans, the engine is adjusted so that the rear is 1-1/2 to 2-

2. The 6L80E AOD trans is bolted to the rear of the engine and then the tail housing is replaced with one for a late-model pickup driveshaft. A custom driveline is then built because the overall length of this engine and tranny is different from the old TH350 and small-block engine that it's replacing.

2. The 6L80E AOD trans is bolted to the rear of the engine and then the tail housing is re

4a. The trans cooler lines are connected from the driver's side of the radiator to the same side of the trans.

4a. The trans cooler lines are connected from the driver's side of the radiator to the sam

4b.

5a. The owner of this truck wanted a column shifter, so this Iditit steering column designed for a 700-R4 was installed. Contrary to popular belief, this six-speed trans only needs a shifter with four forward gear selectors. The Fifth and Sixth overdrive gears are shifted electronically using inputs from the electronic throttle position sensor and manifold absolute pressure sensor, which are already on the engine.

5a. The owner of this truck wanted a column shifter, so this Iditit steering column design

5b.

6. Lokar offers an adjustable column shift linkage if you'd like to keep your factory steering column intact. This Ididit arrangement that came with the column worked out just fine.

Tech TipNew Tranny = New TricksGM loves to be innovative and change things up. There are several versions of the 6L80E tranny in service in various cars and trucks now. The trans used in this truck is the one that comes in the Pontiac GTO and G8 sedans. The fluid pan is 3/4-inch shorter than the pan in the Cadillac version of the same transmission. The interesting thing here is that although this trans has six forward gears, two of them shift electronically, so you can re-use your stock column shifter. Another interesting feature of this tranny is that unlike others, it does not have a dipstick. So, how do you add fluid to it? Well, there's a plug in the side of the trans that is used to fill it. There's another plug at the rear of the trans where the fluid will come out of when it's full. The filling procedure requires warming the trans fluid to 100 degrees, raising the truck in the air safely, and then pulling the plugs and adding the fluid.

Part Seven: Wrapping Up the Install

1a. All LS-series engines use a drive-by-wire accelerator pedal assembly to actuate the throttle body. That is unless, you purchase an aftermarket cable conversion or ditch the fuel injection in favor of a carburetor. S&P fabricator, Guy, built this adapter to mount a '09 Corvette pedal to the firewall of the '68 C10

1a. All LS-series engines use a drive-by-wire accelerator pedal assembly to actuate the th

1b.

2. The LS-3 uses a credit card-style mass airflow sensor and S&P incorporated it into a twin horn air intake. It's important that the maf sensor be matched to the computer so if you grab your drivetrain from a boneyard, be sure to get the MAF sensor and computer from the same vehicle you scab the engine and tranny from.

2. The LS-3 uses a credit card-style mass airflow sensor and S&P incorporated it into a tw

3a. We need a way to light off this monster and because this is the new millennium, a computer will do the job. There are a lot of places to hide the brains of this operation and S&P chose to put this one behind the glove compartment for easy access.

3a. We need a way to light off this monster and because this is the new millennium, a comp

3b. After checking for leaks and double-checking all hose and wiring connections, James loads S&P's own program into the computer and the transmission, then makes final calibrations before taking the truck for a test drive.

3b. After checking for leaks and double-checking all hose and wiring connections, James lo

4a. Here's a good look at the completed engine swap. The serpentine belt system looks great and functions beautifully. The Corvette engine cowling screams performance.

4a. Here's a good look at the completed engine swap. The serpentine belt system looks grea

4b.

4c.

Part Eight: Power to the Pavement!

A weak rearend is a surefire way to break stuff and having the right gearing is imperative to taking advantage of an AOD trans. Our test truck features a new 12-bolt limited-slip differential, 3.73 gearing, 35-spline axles, and 12-inch disc brakes. A DTS rearend cover add lateral bracing and great looks as well.

A weak rearend is a surefire way to break stuff and having the right gearing is imperative

The Man and His Truck

Craig McLaughlin of El Dorado, Kansas, is the lucky soul who gets to mob this bitchin '68 Chevy now. It's got the right stance, killer rolling stock, and now one of the baddest drivetrain swaps we've seen in a long time.